Carrying on from my last post, now completed a diagnostic on the vacuum pump all this seems to working, now testing the servo the pressure builds up to 600mm HG after a minute, (seems a bit slow to me) and when the brake pedal is depressed the pressure drops to about 350-400mm HG then takes a minute again to build up! If the brake pedal is depressed several times the pressure drops to zero.
Is this normal behaviour for a master servo or do you feel this a faulty item. I have changed this with a second hand unit and was a complete nasty job.
Thanks for your assistance in this matter.
Kind regards and drive safe